The loads you've mentioned don't come close to tapping the potential of the Roberts.

Drop the H380 except for bullets weighing 90 gr or less.

RL-22 is the "go to" powder for bullets weighing 100 gr and more. H4831 is a close second.

I don't know your rifle and it's personal characteristics so recommending a load isn't something I'd feel comfortable with. There is also your choice of cases, primers etc that need consideration. With that in mind, the particular loads you mentioned are very soft in any modern firearm. "Modern," means, any rifle other than some of the Mausers and other turn of the century military rifles. Possibly the Japanese WWII stuff.

A chronograph is a necessity when loading the Roberts as this is the only indicator of your rifles personality.

Target velocities for 100 gr bullets is in the 3150 fps range. 110, 115 gr bullets, right at or just below 3100 fps. Easily obtainable with H4831 and RL-22 in "good quality barrels." According to my Hodgdon books, these velocities are obtained with pressures well below 50,000 psi. Can't guarantee the accuracy of the books but I've shot a lot of these loads (mostly hotter) with no problems.

All factory loads, including the +P loads, aren't something you want to try and duplicate but you should run a box of them through the chronograph to see how close to the ammo manufacturers advertised velocities are in your rifle.

If your rifle is a 722 the bullets need to be seated too deep in the case to get the zing you can get out of a rifle with a long magazine (700 classic example). Standard velocity is really tame compared to hot handloads for this round. Hand loads tend to make a real mess under the shoulder of a deer and blow a really big exit hole on broadside shots. Gotta use a strong bullet. My .280 is much easier on meat than my .257 was.

Dog I'll agree with the RL 22 as being a fine powder for the little Bob but I've always done better with IMR 4831 than with Hodgdons, but about the best thing you can do for the .257 Roberts is have an Ackley improved chamber since it has too much taper & is under-loaded to boot it gains more than most & case life is really improved.

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